Process of making fused multifocal lenses



Aug. 17 1926. 1,596,395

L. W. BUGBEE, JR

PROCESS OF MAKING FUSED MULTIFOCAL LENSES Filed Dec. 1925 IE1 l F1 I I 1 1% 2 ll PIE PR3 '5 l/l/l/ 4 I I NVENTOR.

Lu /M #4506555, 1/2.

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Patented Aug. 17, 1926.

UNITED STATES 1,596,395 PATENT OFFICE.

LUCIAN W. BUGBEE, JR., OF'INDIANAPOLIS, INDIANA, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO CONTINENTAL OPTICAL CORPORATION, OF NEW YORK, N. Y., A

CORPORATION OF DELAWARE.

PROCESS OF MAKING FUSED MULTIFOCAL LENSES.

Application file'd December This invention relates to a process of fusing the major and minor elements of a fused bifocal lens, with the minor element mounted on the block with its curved surface to be fused uppermost and the major element superimposed upon said block and minor element so as to cover the minor element.

The chief feature of this invention consists in superimposing the major element on the minor element and block, so that one marginal portion of the major element will rest on the block and the major portion will rest on one margin of the minor element and nowhere else so that during the fusion and as the major element sags and fuses with the minor element, all air will be expelled from between the two elements and all dust and foreign particles kept from between the two elements, whereby a perfect lens will be formed. In such process the major element is formed of crown glass or the like which has a lower melting or softening point than the minor element which may be made of dense barium crown glass.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims.

Fig. 1 is a plan view of the major element with a countersink in it. Fig. 2 is a plan view of the minor element. Fig. 3 is a central vertical section through the major and minor elements mounted on a block preparatory to fusion. Fig. 4 is the same after fusion of the elements. Fig. 5 is a similar section of the: fused lens blank after its removal from t e block. Fig. 6 is a similar section of the finished fused lens. Fig. 7 is a similar section of a modified arrangement. Fig. 8 is a semi-section of the fused blank in the modified process. Fig. 9 is a section similar to Fig. 3 of a modified form.

There is shown in the drawings a major element 10 made of crown glass or the like having a relatively low softening or melting point and provided with a slight countersink 11. The curvature of the countersink need not be carefully made as it need not be exactly the same as the desired final'curvature of the fused surfaces in the finished lens, as in this invention, the curvature of the countersink does not determine such final curvature.

8, 1925. Serial No. 74,206.

barium crown, flint or other hard glass that requires a higher temperature to soften or melt it than is required by the glass forming with a recess 1 1 in which the minor element is seated as shown in Fig. 3 and is so formed that when the minor element is seated its curvature will not be parallel substantially to the curvature of the block but, in the form shown in Fig. 3, it will project farther above the surface of the block at the inner margin of the minor element than at the outer margin, whereby the minor element is mounted at a slight inclination as shown.

Preparatory to fusing, the major element is superimposed upon the block and minor element, as shown in Fig. 3 so that one margin of the major element rests by gravity or other suitable force on the block and the major element is otherwise supported only by the inner margin of the minor element, but the major element entirely covers the minor element and the countersink 11 of the I major element lies above the minor element.

The next step in the process isto heat the elements in the usual manner, preferably at a temperature which will soften the major element but not the minor element. As the major element softens, it will by gravity sag down from the position shown in Fig. 3 to that shown in Fig. 4 and become fused with the minor element. Assembled as shown in Fig. 3, it is noted that there is space between the two elements excepting at the inner margin of the minor element. Hence as the major element sags it will progressively contact with the minor element and thus force out the air between the two elements and avoid the production of bubbles in the finished lens. Also since the major element covers the minor element, it will protect the surfaces of the two elements from dust and foreign particles and leave them clean at the time of fusion. For these reasons a fused lens of high quality is produced by a simple process which avoids cups for prevention of dust and the like getting between the elements before and during fusion, and also gravity or other suitable pressure will cause the major element to stay in place while the minor element is held in place by the seat 14: and the block.

The fused blank is substantially the same as shown in Fig. 5 and the next step in the process is to finish the blank so as to produce the finished lens as shown in Fig. 6.

A modified form of the invention is shown in Fig. 7 where the minor segment is mounted on the blockso that the major element will engage it only at its outer margin and will engage the block at the opposite margin of the major element, whereby there is space between the major element on the one end and the minor element, and block on the other end, whereby as the major element sags during fusion, the air will be expelled automatically from beneath the major element, and the blank produced substantially as shown in Fig. 8.

The modified form shown in Fig. 9{ illustrates the asemblage of parts when the major element 10 is a convex lens instead of a concave lens, as shown in Fig. 3. The only difier-ence is that the top of the block 13 must be concave instead of convex, as shown in Fig. 3.

The invention claimed is:

1. In the process of making fused multifocal lenses wherein there is a major element with a countersink and a minor element to be fused therein, superimposing the major element upon and covering the minor element by engaging the minor element before fusion only at one margin thereof, and then fusing them, whereby as the major element sags during the fusion the air between the two elements will be expelled before ultimate fusion of the two elements.

2. In the process of making fused multifocal lenses, making a minor el'ment of glass requiring a relatively high temperature to soften it and giving to it the curvature ultimately desired for the curvature .of the fused surfaces of the lenses when finished, making a major element of glass which will soften at a lower temperature than said minor element and providing therein a countersink for a minor element and of less curvature than that of the minor element, placing the minor element on the block having a curvature approximately that of the curvature of the major element, and superimposing the major element' on said block and minor element with the major element contacting with the margin of the minor element at one point, and thereafter subjecting the same to a temperature which will soften the major element and cause it to sag and fuse with the minor element.

3. The process of making fused multifocal lenses substantially as set forth in claim 2, providing a recess in the surface of the block which will cause the minor element to extend at one point farther above the general surface of the block than at other points of the margin, substantially as set forth.

In witness whereof, I have hereunto affixed my signature.

LUCIAN w. BUGBEE, JR. 

